I note that we had some issues with mesh handling in Warp3D some time ago that were fixed by changing to a signed version of zlib.net.dll which is used by libomv for OpenSim. I am wondering if it could be that one of the .dll we use in warp3D has a security/signing issue that could be showing after the update from Windows 1809 to 1903. Security changes are one likely source of the problems.